Field of the Invention
The present invention relates to a projector.
Description of the Related Art
Today, a data projector is commonly used as an image projector for projecting a picture on a personal computer, a video image, and an image based on image data stored in a memory card or the like on a screen. This type of projector condenses light emitted from a light source onto a digital micromirror device (DMD) or a display element such as a liquid crystal plate and displays a color image on the screen.
In this data projector, laser light emitted from a laser light source, for example, passes through a collimator lens, spreads on a diffusion plate, and enters a microlens array. The laser light is made to enter the microlens array so as to be widely applied thereto by the diffusion plate. Thereafter, the laser light is condensed by a condenser lens and is applied to a display element through a prism. The image light formed on the display element is projected on the screen by a projection optical system.
Japanese Patent Application Laid-Open No. 2015-145972 discloses a projector which diffuses laser light by using a diffusion plate and then condenses the laser light by using a condenser lens to apply the laser light to a display element. In addition, the Patent Document 1 also discloses that the light having passed through the diffusion plate is passed through a lens array having a plurality of lenses constituting an integrator optical system and then condensed by the condenser lens. According to this configuration, coherent light emitted from a light source device is diffused by the diffusion plate so as to be a luminous flux having a uniform illuminance distribution by the lens array which is an integrator optical system and is able to be applied to the display element.
Moreover, Japanese Patent Application Laid-Open No. 2012-73489 discloses a projector wherein a light source unit includes: an excitation light source which emits predetermined wavelength band light; and a light emitting plate having a fluorescence emitting section in which a phosphor layer for emitting predetermined wavelength band light is laid with the surface as a reflective surface and with light emitted from the excitation light source as excitation light and a diffusion section which diffuses and reflects the light emitted from the excitation light source. A total internal reflection (TIR) prism is arranged between the light emitting plate and the excitation light source. Light from the light emitting plate passes through the TIR prism and is applied to a display element via a microlens array, a condenser lens, and a reverse total internal reflection (RTIR) prism, and ON light from the display element is made to enter the RTIR prism again and projected on a screen via a projection optical system.
The techniques disclosed in Japanese Patent Application Laid-Open No. 2015-145972 and Japanese Patent Application Laid-Open No. 2012-73489 have a problem that the laser light enters the microlens array with an oval cross-sectional shape and therefore, in the case of a small incident range, the luminance balance deteriorates on the right and left sides of a projected picture, by which the center is light while the corners are dark and a lattice-shaped pattern appears due to an influence of diffraction of the microlens array.
An object of the present invention is to provide a light source device capable of dispersing and uniforming the illuminance distribution or the lattice pattern on the projected picture by arranging a diffusion plate on the emission side of the microlens array and to provide a projector including the light source device.